1. Technical Field
The present invention relates an electro-optical device, a method for manufacturing such an electro-optical device, and an electronic apparatus.
2. Related Art
In general, electro-optical devices, for example, liquid crystal devices for displaying images using electro-optical materials such as liquid crystals, each include a pair of substrates and a liquid crystal sandwiched therebetween. An electro-optical device such as an active matrix-type liquid crystal device driven by thin-film transistors (TFTs) or thin-film diodes (TFDs) includes pixel electrodes and switching elements that are arranged above an element substrate (active matrix substrate) so as to correspond to intersections of many scanning lines (gate lines) and data lines (source lines) extending lengthwise or crosswise.
The switching elements such as TFTs are turned on by on-signals applied to the scanning lines, so that image signals transmitted through the data lines are written on the pixel electrodes, which are transparent and are made of indium tin oxide (ITO). Voltages corresponding to the image signals are thereby applied to a liquid crystal layer sandwiched between a counter electrode and the pixel electrodes, whereby the alignment of liquid crystal molecules is varied. That is, the transmittance of pixels is varied such that light beams passing through the pixel electrodes and the liquid crystal layer are varied depending on the image signals, whereby an image is displayed.
The element substrate, on which the switching elements are arranged, is prepared by depositing a semiconductor thin-film, insulating thin-film, or conductive thin-film having a predetermined pattern on a glass or quartz plate.
Properties of the TFTs are varied by the effect of light. If channel regions of the TFTs are irradiated with light, photo-leakage currents are caused, whereby the TFT properties are deteriorated. This causes a nonuniform image, a reduction in contrast, and deteriorations in flicker properties.
In order to shield the channel regions of the TFTs or regions adjacent to the channel regions from light, the element substrate or a counter substrate has a light-shielding film for blocking light. Incident light rays are scattered or multiply reflected by wires or leads and then applied to the TFTs. Japanese Unexamined Patent Application Publication No. 2003-140566 (hereinafter referred to as Patent Document 1) discloses an electro-optical device in which a light-shielding film is placed close to channel regions of TFTs such that these channel regions are securely shielded from light.
In the electro-optical device disclosed in Patent Document 1, an interlayer insulating layer overlying gates has a groove extending to an etching stopper layer covering the gates and the light-shielding film is placed in the groove such that the light-shielding film is located close to the channel regions.
However, the electro-optical device disclosed in Patent Document 1 has a problem in that these channel regions cannot be securely shielded from light if incident light is scattered or multiply reflected repeatedly.